When a systems contains tens of thousands of documents (as mine does) search will ALWAYS return more results than are useful. Often, you are not sure what words will occur in the document you are looking for, making search pointless. What you need is a way to browse. Browsing is best when there is a granular filing system based on folders/categories and sub-folders/categories. This does not have a negative impact on search but it does make finding a document much easier when you are not sure of the exact contents. I would find this feature extremely useful.

This feature is a must. Creating sub categories, so that files could be organised in more efficient way is far more important than multiple upload and fancy interface.
Nevertheless, all of the options listed in the Uservoice are important so that project stays active.